package zijie;

/**
 * 给你一个由 '1'（陆地）和 '0'（水）组成的的二维网格，请你计算网格中岛屿的数量。
 *
 * 岛屿总是被水包围，并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。
 *
 * 此外，你可以假设该网格的四条边均被水包围。
 *
 *
 */
public class NumIslands_200_21 {
    private int res;
    public int numIslands(char[][] grid) {
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if(grid[i][j] == '1'){
                    dfs(grid,i,j);
                    res ++;
                }
            }
        }
        return res;

    }
    private void dfs(char[][] grid,int row, int col){
        if(row >= grid.length
                || col >= grid[0].length
                || row < 0
                || col < 0){
            return;
        }
        if(grid[row][col] != '1'){
            return;
        }
        grid[row][col] = '2';
        dfs(grid,row - 1,col);
        dfs(grid,row + 1,col);
        dfs(grid,row ,col - 1);
        dfs(grid,row, col + 1);
    }

    public int numIslands2(char[][] grid) {
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if(grid[i][j] == '1'){
                    dfs2(grid,i,j);
                    res ++;
                }
            }
        }
        return res;
    }

    private void dfs2(char[][] grid, int row,int col){
        if(row >= grid.length || col >= grid[0].length || row < 0 || col < 0){
            return;
        }
        if(grid[row][col] != '1'){
            return;
        }
        grid[row][col] = '2';
        dfs2(grid,row - 1, col);
        dfs2(grid,row + 1,col);
        dfs2(grid,row,col - 1);
        dfs2(grid,row,col + 1);



    }

}
